Penning series 10 episode The Empress of Mars wasn’t Mark Gatiss’s last contribution to Doctor Who after all: the writer and actor is set to star in this year’s Christmas special alongside Peter Capaldi and David Bradley.

The news was confirmed rather casually as Gatiss partook in an interview with Empire magazine at Comic Con, alongside Capaldi and Steven Moffat. Watch the interview below: The news is revealed around the 11:30 mark.

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“It was a privilege, an honour and a thrill,” Gatiss said of his role.

The trio were tight-lipped on the specifics of his character, but the outgoing Doctor added that the character had “a resonant echo in the whole Doctor Who story”.

This appearance will mark the fourth character that Gatiss has played in the sci-fi series, having previously appeared as a mutated scientist called Professor Lazarus in 2007 episode The Lazarus Experiment, voiced a World War II pilot nicknamed ‘Danny Boy’ in 2010/2011 episodes Victory of the Daleks and A Good Man Goes to War, and a mysterious figure called Gantok in The Wedding of River Song.

Gatiss has also written ten episodes for the series since it returned to 2005 as well as creating 2013 “making-of” drama An Adventure in Space and Time, where he actually cast Bradley as First Doctor actor William Hartnell prior to his appearance as the Doctor himself in the main series this year.

But of course Gatiss’s most recent contribution to the Whoniverse was the aforementioned Ice Warrior episode Empress of Mars, which he had previously suggested could be the end of his Doctor Who career.

“I’ve no idea,” he told RadioTimes.com a few months ago when asked whether he would continue writing for Doctor Who when new showrunner Chris Chibnall took over. “It’s a funny thing, an end of an era.

“Obviously working very closely with Steven I feel it more than when Russell [T Davies, previous showrunner on Doctor Who] left. I suppose there was more of a sense of continuity there, but I’ve no idea,” he added.

“I’ve had a fantastic run on my favourite show, so if I don’t do anymore then I’m perfectly sanguine. But who knows?”

Who knows indeed – because clearly, longtime creative partner Steven Moffat (with whom Gatiss created fellow BBC series Sherlock and future project Dracula) couldn’t bear to write his last episode without having his old pal around in some form, giving Gatiss one last crack of the Whoniverse whip.

And even if this episode finally is the end of Gatiss’ Who experience, this new role will definitely make him one of the people with the longest and most complicated entries on the Doctor Who wiki page after the festive special airs – and in the end, isn’t that what it’s all about?

Doctor Who will return to BBC1 this Christmas